Fin field effect transistor (FinFET) is superior over bulk metal oxide semiconductor FET (MOSFET) in the aspects of: reduced leakage, excellent sub-threshold slop, and better voltage gain without degradation of noise or linearity. Therefore, FinFET structure is desired device architecture for high end devices such as microprocessors. A FinFET is a unipolar transistor which only uses one kind of charge carrier. On the other hand, a bipolar junction transistor (BJT) uses both electron and hole charge carriers. The BJT may be manufactured in two types, NPN and PNP, and may be used as, for example, an amplifier or a switch for variety of electronic devices. An NPN BJT includes two regions of N-type semiconductor material constituting the emitter and collector regions, and a region of P-type semiconductor material located between the two regions of N-type semiconductor material constituting the base region. A PNP BJT consists one region of N-type semiconductor material between two regions of P-type semiconductor material.
To take advantage of the positive characteristics of the above described two types of transistors, FinFETs may be combined with BJTs in bipolar complementary metal-oxide-semiconductor (BiCMOS) integrated circuits. III-V semiconductors are promising materials for BiCMOS devices because of their high-carrier mobility. In the process of forming the BiCMOS devices, III-V semiconductors may be grown from a sidewall of a semiconductor mandrel structure. The grown III-V semiconductors described above may not be compatible with silicon device which usually requires high processing temperatures. As such, there is a need for providing a method in which III-V semiconductors can be grown from a sidewall of a semiconductor mandrel structure without being subjected to the high processing temperatures typically used in forming the silicon devices.